Gravitational waves could settle mystery of the universe's expansion

LIGO’s detectors could help resolve the debate over how fast the universe is expanding

Christian Offenberg / Alamy Stock Photo

Cosmologists can’t agree on how fast the universe is expanding because the two different methods they use to find out give distinctly different results. Now a third method involving gravitational waves is looking more promising, and it could help break the deadlock.

Gravitational waves are the minuscule ripples in space-time that were discovered in 2015 by the Laser Interferometer Gravitational-Wave Observatory, better known as LIGO. They are produced when gigantic objects like black holes or neutron stars smash together. …